Effect of sesamol on diabetes-associated cognitive decline in rats

Huperzine A ameliorates cognitive deficits in streptozotocin-induced diabetic rats

The present study was designed to probe the effects of Huperzine A (HupA) on diabetes-associated cognitive decline (DACD) using a streptozotocin (STZ)-injected rat model. Diabetic rats were treated with HupA (0.05 and 0.1 mg/kg) for seven weeks. Memory functions were evaluated by the water maze test. Nissl staining was selected for detecting neuronal loss. Protein and mRNA levels of brain-derived neurotrophic factor (BDNF) were analyzed by ELISA and real-time PCR, respectively. The activities of choline acetylase (ChAT), Acetylcholinesterase (AChE), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), NF-κB p65 unit, TNF-α, IL-1β, IL-6 and caspase-3 were measured using corresponding kits. After seven weeks, diabetic rats exhibited remarkable reductions in: body weight, percentage of time spent in target quadrant, number of times crossing the platform, ChAT and BDNF levels, SOD, GSH-Px and CAT accompanied with increases in neuronal damage, plasma glucose levels, escape latency, mean path length, AChE, MDA level as well as CAT, NF-κB p65 unit, TNF-α, IL-1β, IL-6 and caspase-3 in cerebral cortex and hippocampus. Supplementation with HupA significantly and dose-dependently reversed the corresponding values in diabetes. It is concluded that HupA ameliorates DACD via modulating BDNF, oxidative stress, inflammation and apoptosis.

Chrysin ameliorates diabetes-associated cognitive deficits in Wistar rats

Chrysin (CH) is an important natural plant flavonoid and possesses diverse pharmacological activities. Our present investigations aimed to assess the neuroprotection of CH against diabetes-associated cognitive decline (DACD) in a rat model of diabetes and exploring its potential mechanism. Diabetic model was induced by intraperitoneal injection of streptozotocin. Then, they were treated with vehicle or CH by doses of 30 and 100 mg/kg for 26 days. Learning and memory function was evaluated by Morris water maze test. The oxidative indicators [malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH)], NF-κB p65 unit, TNF-α, IL-1β, IL-6 and caspase-3 were measured in cerebral cortex and hippocampus using corresponding commercial kits. The diabetic rats showed marked reductions in body weight, percentage of time spent in target quadrant and number of times of crossing platform, coupled with increases in plasma glucose levels, escape latency, mean path length and oxidative stress (increased MDA level and decreased CAT and SOD as well as reduced GSH), NF-κB p65 unit, TNF-α, IL-1β, IL-6 and caspase-3 in cerebral cortex and hippocampus. Moreover, CH supplement dramatically reversed the corresponding behavioral, biochemical and molecular alterations in diabetes. The alterations of swimming speed among different groups were not observed after CH adminstration. In conclusion, our current work discloses that CH remarkably alleviates DACD and suggests that oxidative stress, inflammation and apoptotic cascades are linked with diabetes-associated cognitive deficits. These findings point toward the therapeutic potential of CH in DACD.

Luteolin protects against high fat diet-induced cognitive deficits in obesity mice

The epidemic and experimental studies have confirmed that the obesity can lead to neuroinflammation, neurodegenerative diseases and adversely affect cognition. Despite the numerous elucidations on the impact of obesity on cognition decline, the contributors to the impairments in obesity remain unclear. Male C57BL/6J mice were fed either a control or high-fat diet (HFD) for 16 weeks and then randomized into four groups treated with their respective diets for 4 weeks including control diet (CD); control diet+luteolin (CDL); high-fat diet (HFD), high-fat diet+luteolin (HFDL). The dose of luteolin was 10mg/kg, oral. We showed that adding luteolin in high-fat diet can significantly reduce body weight gain, food intake and plasma cytokines as well as improving glucose metabolism of mice on HFD. Importantly, we showed that luteolin treatment had the effects of alleviating neuroinflammation, oxidative stress and neuronal insulin resistance in the mouse brain, restored blood adipocytokines level to normal. Furthermore, luteolin increased the level of brain-derived neurotrophic factor (BDNF), the action of synapsin I (SYP) and postsynaptic density protein 95 (PSD-95) in the cortex and hippocampus as to that the behavioral performance in Morris water maze (MWM) and step-through task were significantly improved. These results indicate a previously unrecognized potential of luteolin in alleviating obesity-induced cognitive impairment for type-2 diabetes mellitus and Alzheimer disease (AD).

Oxymatrine attenuates diabetes-associated cognitive deficits in rats

AIM

Oxymatrine (OMT) is the major quinolizidine alkaloid extracted from the root of Sophora flavescens Ait (the Chinese herb Kushen) and exhibits diverse pharmacological actions. In this work we investigated the effects of OMT on diabetes-associated cognitive decline (DACD) in a rat model of diabetes and explored the mechanisms of action.

METHODS

Male Wistar rats were injected with streptozotocin (65 mg/kg, ip) once to induce diabetes. The rats were then treated with vehicle or OMT (60 or 120 mg/kg per day, ip) for 7 weeks. Memory function was assessed using Morris water maze test. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), NF-κB p65 unit, TNF-α, IL-1β and caspase-3 in the cerebral cortex and hippocampus were quantified.

RESULTS

The diabetic rats exhibited markedly reduced body weight and increased plasma glucose level. The memory function of the rats assessed using Morris water maze test showed significant reduction in the percentage of time spent in the target quadrant and the number of times crossing the platform, coupled with markedly prolongation of escape latency and mean path length. Moreover, the rats showed oxidative stress (significantly increased MDA, decreased SOD and reduced GSH levels), as well as significant increases of NF-κB p65 unit, TNF-α, IL-1β and caspase-3 levels in the cerebral cortex and hippocampus. Chronic treatment with OMT dose-dependently reversed these behavioral, biochemical and molecular changes in the diabetic rats. However, the swimming speed had no significant difference among the control, diabetic and OMT-treated diabetic rats.

CONCLUSION

Chronic treatment with OMT alleviates diabetes-associated cognitive decline in rats, which is associated with oxidative stress, inflammation and apoptotic cascades.

Reversal of neurobehavioral and neurochemical alterations in STZ-induced diabetic rats by FeTMPyP, a peroxynitrite decomposition catalyst and 1,5-Isoquinolinediol a poly(ADP-ribose) polymerase inhibitor

OBJECTIVE

In this study, we have evaluated the involvement of nitrosative stress and poly-ADP ribosyl polymerase (PARP) in diabetes induced neurobehavioral and neurochemical changes using pharmacological agents peroxynitrite decomposition catalyst (FeTMPyP) and a PARP inhibitor (1,5-Isoquinolinediol) in diabetic brains.

METHODS

The extent of neurobehavioral changes was assessed by functional observation battery, motor coordination activity (rota rod performance) and passive avoidance test. Neurochemical changes were assessed by measuring nicotinamide adenine dinucleotide (NAD), malondialdehyde, acetylcholinesterase, neurotransmitters (GABA and glutamate) levels in the hippocampus. GABA and glutamate were measured by high-performance liquid chromatography with electrochemical detection method.

RESULTS

Two weeks' treatment with FeTMPyP (3 mg/kg, i.p.) and 1,5-Isoquinolinediol (3 mg/kg, i.p.) improved the cognitive deficits in diabetic rats as observed in passive avoidance test. Both the agents inhibited lipid peroxidation and improves the acetylcholinesterase level in the hippocampus. 1,5-Isoquinolinediol treatment also improves the NAD, neurotransmitter level in the hippocampus.

DISCUSSION

These results suggest that peroxynitrite decomposition catalyst and PARP inhibitor have beneficial effects in neurobehavioral alterations induced by diabetes. Improvement in neurobehavioral alteration may be attributed to reversal of neurotransmitter homeostasis deficits.

Diabetes cognitive impairments and the effect of traditional chinese herbs

The problem of cognitive impairment resulting from diabetes is gaining more acceptance and attention. Both type 1 and type 2 diabetes mellitus have been proved to be associated with reduced performance on numerous domains of cognitive function. Although the exact mechanisms of cognitive impairments in diabetes have not been completely understood, hyperglycemia and insulin resistance seem to play significant roles. And other possible risk factors such as hypoglycemia, insulin deficiency, vascular risk factors, hyperactive HPA axis, depression, and altered neurotransmitters will also be examined. In the meanwhile, this review analyzed the role of the active ingredient of Chinese herbal medicine in the treatment of diabetes cognitive impairments.

Fish oil improves learning impairments of diabetic rats by blocking PI3K/AKT/nuclear factor-κB-mediated inflammatory pathways

Previous research has demonstrated that diabetes induces learning and memory deficits. However, the mechanism of memory impairment induced by diabetes is poorly understood. Dietary fatty acids, especially polyunsaturated fatty acids, have been shown to enhance learning and memory and prevent memory deficits in various experimental conditions. The present study investigated the effects of fish oil supplementation on the lipid peroxidation, inflammation and neuron apoptosis in the hippocampus of streptozotocin (STZ)-induced diabetes rats. The effects of diabetes and fish oil treatment on the spatial learning and memory were also evaluated using the Morris Water Maze. STZ-induced diabetes impaired spatial learning and memory of rats, which was associated with the inflammation, oxidative stress and apoptosis of hippocampal neurons. Fish oil administration ameliorated cognitive deficit, reduced oxidative stress and tumor necrosis factor α (TNF-α), protected the hippocampal neurons by increasing Protein Kinase B (AKT) phosphorylation and decreasing caspase-9 expression. These results suggested that the principle mechanisms involved in the antidiabetic and neuroprotective effect of fish oil were its antioxidant, anti-inflammatory and anti-apoptosis potential, supporting a potential role for fish oil as an adjuvant therapy for the prevention and treatment of diabetic complications.

Carvacrol attenuates diabetes-associated cognitive deficits in rats

Carvacrol (CAR), a naturally occurring phenolic monoterpene, has been demonstrated to possess various biological actions. The present study was designed to investigate the neuroprotective effect of CAR on diabetes-associated cognitive deficit (DACD) in a rat model of diabetes and exploring its potential molecular mechanism. Diabetic rats were treated with CAR by the doses of 25, 50, and 100 mg/kg for 7 weeks. Morris water maze was used for behavioral evaluation of memory. Cytoplasmic and nuclear fractions of cerebral cortex and hippocampus were prepared for the quantification of oxidative stress (MDA, SOD, and GSH), NF-κB p65 unit, TNF-α, IL-1β, and caspase-3. After 7 weeks of streptozotocin injection, the rats produced remarkable increase in escape latency, coupled with increased oxidative stress (increased MDA level and decreased SOD as well as reduced GSH), NF-κB p65 unit, TNF-α, IL-1β, and caspase-3 in different regions of diabetic rat brain. Interestingly, coadministration of CAR significantly and dose-dependently prevented behavioral, biochemical, and molecular changes associated with diabetes. In summary, our findings provide the first evidence that CAR can remarkably attenuate DACD and suggest the involvement of oxidative stress, inflammation, and apoptotic cascades in the development of cognitive impairment caused by diabetes. The pharmacological effect of CAR suggests that it may be used as a promising agent for the treatment of conventional antihyperglycemic regiments as well as DACD.

Luteolin attenuates diabetes-associated cognitive decline in rats

Diabetes mellitus can cause dysfunction of the central nervous system called "diabetic encephalopathy". Although various oral drugs are used to treat diabetes, they do not prevent the development of diabetes-associated cognitive decline in rats, and novel strategies for the prevention and treatment are urgently needed. Luteolin, a flavonoid isolated from Cirsium japonicum, has antioxidant, anti-inflammatory and neuroprotective activities. However, no report is available on influence of luteolin on streptozotocin-induced memory impairment. Therefore, we tested its influence against cognitive dysfunction in streptozotocin-induced diabetic rats using Morris water maze test. Nissl's staining, choline esterase (ChE) activity as marker of cholinergic function and oxidative stress were assessed in the cerebral cortex and hippocampus to evaluate the neuropathological changes and the effects of luteolin on diabetic rats. The results showed that streptozotocin-induced diabetes produced obvious neuron damage and cognitive dysfunction coupling with markedly increased oxidative stress and ChE activity in the brain. In contrast, chronic treatment with luteolin (50 and 100mg/kg) improved neuronal injury and cognitive performance by attenuating oxidative stress and ChE activity in diabetic rats. In conclusion, the present study suggested that oral supplementation of luteolin might be a potential therapeutic strategy for the treatment and/or prevention of diabetic encephalopathy.

Effect of sesamol on the pathophysiological changes induced by surgical menopause in rodents

OBJECTIVE

Estrogen deprivation after menopause is associated with increased oxidative stress. The present study was designed to study the role of sesamol (3,4-methylenedioxyphenol), a phenolic antioxidant and anti-inflammatory molecule, in oxidative stress-induced changes in three major affected organ systems, the central nervous system, the cardiovascular system and the skeletal system in ovariectomized rats, a widely used animal model of menopause.

DESIGN

Animals were divided into eight different groups (n = 6-8). Five groups underwent ovariectomy; starting from the 2nd day of ovariectomy, three of these groups received sesamol (2, 4, 8 mg/kg) and the fourth group was administered α-tocopherol (100 mg/kg) orally for 7 weeks. The fifth ovariectomized group did not receive any drug treatment. Rats in the naïve (non-operated) and sham-operated groups did not receive any drug treatment, while the eighth group consisted of naïve animals which were treated for 7 weeks with only sesamol 8 mg/kg orally daily. After 7 weeks, animals were subjected to testing of behavioral paradigms (elevated plus maze and Morris water maze for assessment of anxiety and memory, respectively) 24 h after the last dose. After behavioral studies, animals were sacrificed for various biochemical estimations.

RESULT

Administration of sesamol (2, 4, 8 mg/kg orally) to ovariectomized rats for 7 weeks significantly and dose-dependently improved memory, attenuated anxiety, decreased oxidative stress in brain, improved the serum lipid profile and reduced serum tumor necrosis factor-α levels when compared with ovariectomized control rats. Similar protective effects were observed in the case of the skeletal system studies. Sesamol increased the bone ash content and the mechanical stress parameters in treated groups.

CONCLUSION

The results emphasize the involvement of oxidative stress and inflammation in the development of ovariectomy-induced pathophysiological changes and point towards the therapeutic potential of sesamol in menopausal pathologies.

Diabetes as a chronic metabolic stressor: causes, consequences and clinical complications

Diabetes mellitus is an endocrine disorder resulting from inadequate insulin release and/or reduced insulin sensitivity. The complications of diabetes are well characterized in peripheral tissues, but there is a growing appreciation that the complications of diabetes extend to the central nervous system (CNS). One of the potential neurological complications of diabetes is cognitive deficits. Interestingly, the structural, electrophysiological, neurochemical and anatomical underpinnings responsible for cognitive deficits in diabetes are strikingly similar to those observed in animals subjected to chronic stress, as well as in patients with stress-related psychiatric illnesses such as major depressive disorder. Since diabetes is a chronic metabolic stressor, this has led to the suggestion that common mechanistic mediators are responsible for neuroplasticity deficits in both diabetes and depression. Moreover, these common mechanistic mediators may be responsible for the increase in the risk of depressive illness in diabetes patients. In view of these observations, the aims of this review are (1) to describe the neuroplasticity deficits observed in diabetic rodents and patients; (2) to summarize the similarities in the clinical and preclinical studies of depression and diabetes; and (3) to highlight the diabetes-induced neuroplasticity deficits in those brain regions that have been implicated as important pathological centers in depressive illness, namely, the hippocampus, the amygdala and the prefrontal cortex.

Ginsenoside Re attenuates diabetes-associated cognitive deficits in rats

OBJECTIVE

This study was designed to investigate the effect of ginsenoside Re (Re) on cognitive functions, oxidative stress and inflammation in streptozotocin-induced diabetic rats.

RESEARCH DESIGN AND METHOD

Diabetic rats were treated with Re (40mg/kg) for 8weeks, blood glucose and body weight were measured monthly and weekly, respectively. Cognitive performances were evaluated with Morris water maze. Brain was obtained for measurements of TNF-α and malondialdehyde (MDA) contents in both temporal cortex and hippocampus, blood was collected for assays of TNF-α, MDA and reduced glutathione (GSH) levels.

RESULTS

Learning and memory abilities were significantly (both P<0.01) impaired in diabetic rats, accompanied by the marked (all P<0.01) elevations of TNF-α and MDA levels in temporal cortex and hippocampus. Increment of MDA and decrement of GSH in serum also occurred with significant differences (both P<0.01). Chronic treatment with Re markedly (P<0.05) improved the cognition of diabetic rats, evidenced by the decreased escape latency and the increased percentage of time spent in the target quadrant. Furthermore, Re treatment remarkably (P<0.05) reduced the levels of TNF-α and MDA in both brain areas of diabetic rats. Decline of MDA level and elevation of GSH level in serum were also seen in Re-treated diabetic rats, coupled with decrease in serum glucose level, all with statistically significant differences.

CONCLUSIONS

Our findings firstly provide the first evidence that ginsenoside Re can remarkably attenuate diabetes-associated cognitive decline, secondly confirm the involvement of oxidative stress and inflammation in the development of cognitive impairment caused by diabetes, finally point toward the potential of ginsenoside Re as an adjuvant therapy to conventional anti-hyperglycemic regimens as well as diabetes-associated cognitive decline.

Neuropsychopharmacological effect of sesamol in unpredictable chronic mild stress model of depression: behavioral and biochemical evidences

RATIONALE

A complex relationship exists among stressful situations, body's reaction to stress, and the onset of clinical depression. Chronic unpredictable stressors can produce a situation similar to clinical depression, and such animal models can be used for the preclinical evaluation of antidepressants. Many findings have shown that the levels of proinflammatory cytokines (e.g., TNF-α) and oxidative stress (increased lipid peroxidation, decreased glutathione levels, and endogenous antioxidant enzyme activities) are increased in patients with depression. Sesamol, a phenolic derivative with a methylenedioxy group, is a potent inhibitor of cytokine production as well as an antioxidant.

OBJECTIVES

The present study was designed to investigate the effect of sesamol on unpredictable chronic stress-induced behavioral and biochemical alterations in mice.

METHODS

Animals were subjected to different stress paradigms daily for a period of 21 days to induce depressive-like behavior. The sucrose preference, immobility period, locomotor activity, memory acquisition, and retention were evaluated.

RESULTS

Chronic treatment with sesamol significantly reversed the unpredictable chronic stress-induced behavioral (increased immobility period, reduced sucrose preference), biochemical (increased lipid peroxidation and nitrite levels; decreased glutathione levels, superoxide dismutase and catalase activities), and inflammation surge (serum TNF-α) in stressed mice.

CONCLUSION

The study revealed that sesamol exerted antidepressant-like effects in behavioral despair paradigm in chronically stressed mice, specifically by modulating central oxidative-nitrosative stress and inflammation.

Exacerbation of ischemia-induced amyloid-beta generation by diabetes is associated with autophagy activation in mice brain

To evaluate effect of diabetes on transient ischemia-induced brain damage and autophagy activity, streptozotocin (STZ)-induced diabetic mellitus (DM) mice were subjected to transient common carotid artery occlusion (CCAO) operation. After the operation, immunohistochemistry and transmission electron microscopy (EM) were performed to investigate the astrocytes activation, amyloid-beta protein (Abeta) expression and accumulation of autophagy-like vacuoles containing electron-dense material (avd); and hallmarks of autophagy, the microtubule-associated protein light chain 3 (LC3)-II, was detected by western blot analysis. The results showed that DM amplified stroke-induced astrocytes activation and Abeta generation. Western blot analysis showed that LC3-II conjugate was drastically up-regulated at early stages post ischemia and it last for at least 72h in DM mice brain. DM mice demonstrated increased baseline level of LC3-II as comparing to normal mice; DM also amplified stroke-induced LC3-II level. Under EM, avd was most markedly accumulated in neurons of DM mice brain after ischemia. Immunofluorescence double-staining showed that most Abeta and autophagosomes co-localized. Therefore, our results suggested that exacerbation of ischemia-induced Abeta generation by diabetes might be associated with autophagy activation in mice brain, and modulating neuronal autophagy might be a new therapeutic strategy to depress the risk of development of dementia in diabetic patients with stroke.

Attenuation of renoinflammatory cascade in experimental model of diabetic nephropathy by sesamol

Diabetes has become the most common single cause of end-stage renal disease (ESRD) in the United States and Europe. Approximately 30-40% of patients with type I and 15% with type II diabetes mellitus develop end ESRD. The study was designed to evaluate the impact of sesamol on renal function and renoinflammatory cascade in streptozotocin (STZ)-induced diabetes. STZ-induced diabetic rats were treated with sesamol (2, 4, and 8 mg/kg/day; po) or with vehicle from the fifth to eighth weeks. After 8 weeks, urine albumin excretion, urine output, serum creatinine, blood urea nitrogen, creatinine, and urea clearance were measured. Cytoplasmic and nuclear fractions of kidney were prepared for the quantification of oxidative-nitrosative stress (lipid peroxidation, superoxide dismutase, catalase, nonprotein thiols, total nitric oxide), tumor necrosis factor-alpha (TNF-alpha), tissue growth factor-1 beta (TGF-beta1), p65 subunit of NFkappabeta, and caspase-3. After 8 weeks of STZ injection, the rats produced significant alteration in renal function, increased oxidative-nitrosative stress, TNF-alpha, TGF-beta1, caspase-3 activity in cytoplasmic lysate, and active p65 subunit of NFkappabeta in nuclear lysate of kidney of diabetic rats. Interestingly, co-administration of sesamol significantly and dose-dependently prevented biochemical and molecular changes associated with diabetes. Moreover, diabetic rats treated with insulin-sesamol combination produced more pronounced effect on molecular parameters as compared to their respective groups. The data reveal that sesamol modulates the release of profibrotic cytokines, oxidative stress, ongoing chronic inflammation, and apoptosis and thus exerts a marked renoprotective effect.

Administration of sesamol improved blood-brain barrier function in streptozotocin-induced diabetic rats

Uncontrolled or poorly controlled blood glucose during diabetes is an important factor in worsened vascular function. While evidence suggests that hyperglycemia-induced oxidative stress plays a prominent role in development of microangiopathy of the retina, kidney, and nerves, the role oxidative stress plays on blood-brain barrier (BBB) function and structure has lagged behind. In this study, a natural antioxidant, sesamol, was administered to streptozotocin (STZ)-induced diabetic rats to examine the role that oxidative stress plays on BBB structure and function. Experiments were conducted at 56 days after STZ injection. Male Sprague-Dawley rats randomly were divided into four treatment groups CON--control; STZ--STZ-induced diabetes; CON + S--control + sesamol; STZ + S--STZ-induced diabetes + sesamol. Functional and structural changes to the BBB were measured by in situ brain perfusion and western blot analysis of changes in tight junction protein expression. Oxidative stress markers were visualized by fluorescent confocal microscopy and assayed by spectrophotometric analysis. Results demonstrated that the increased BBB permeability observed in STZ-induced diabetic rats was attenuated in STZ + S rats to levels observed in CON. Sesamol treatment reduced the negative impact of STZ-induced diabetes on tight junction protein expression in isolated cerebral microvessels. Oxidative stress markers were elevated in STZ as compared to CON. STZ + S displayed an improved antioxidant capacity which led to a reduced expression of superoxide and peroxynitrite and reduced lipid peroxidation. In conclusion, this study showed that sesamol treatment enhanced antioxidant capacity of the diabetic brain and led to decreased perturbation of hyperglycemia-induced changes in BBB structure and function.

Effects of adult-onset streptozotocin-induced diabetes on the rat brain antioxidant status and the activities of acetylcholinesterase, (Na(+),K (+))- and Mg(2+)-ATPase: modulation by L-cysteine

Uncontrolled diabetes is known to affect the nervous system. The aim of this study was to investigate the effect of the antioxidant L: -cysteine (Cys) on the changes caused by adult-onset streptozotocin (STZ)-induced diabetes on the rat brain total antioxidant status (TAS) and the activities of acetylcholinesterase (AChE), (Na(+),K(+))-ATPase and Mg(2+)-ATPase. Thirty-eight male Wistar rats were divided into six groups: C(A) (8-week-control), C(B) (8-week-control + 1-week-saline-treated), C + Cys (8-week-control + 1-week-Cys-treated), D(A) (8-week-diabetic), D(B) (8-week-diabetic + 1-week-saline-treated) and D + Cys (8-week-diabetic + 1-week-Cys-treated). All diabetic rats were once treated with an intraperitoneal (i.p.) STZ injection (50 mg/kg body weight) at the beginning of the experiment, while all Cys-treated groups received i.p. injections of Cys 7 mg/kg body weight (daily, for 1-week, during the 9th-week). Whole rat brain parameters were measured spectrophotometrically. In vitro incubation with 0.83 mM of Cys or 10 mM of STZ for 3 h was performed on brain homogenate samples from groups C(B) and D(B), in order to study the enzymes' activities. Diabetic rats exhibited a statistically significant reduction in brain TAS (-28%, D(A) vs C(A);-30%, D(B) vs C(B)) that was reversed after 1-week-Cys-administration into basal levels. Diabetes caused a significant increase in AChE activity (+27%, D(A) vs C(A); +15%, D(B) vs C(B)), that was further enhanced by Cys-administration (+57%, D + Cys vs C(B)). The C + Cys group exhibited no significant difference compared to the C(B) group in TAS (+2%), but showed a significantly increased AChE activity (+66%, C + Cys vs C(B)). Diabetic rats exhibited a significant reduction in the activity of Na(+),K(+)-ATPase (-36%, D(A) vs C(A);-48%, D(B) vs C(B)) that was not reversed after 1-week Cys administration. However, in vitro incubation with Cys partially reversed the diabetes-induced Na(+),K(+)-ATPase inhibition. Mg(2+)-ATPase activity was not affected by STZ-induced diabetes, while Cys caused a significant inhibition of the enzyme, both in vivo (-14%, C + Cys vs C(B);-17%, D + Cys vs C(B)) and in vitro (-16%, D(B) + in vitro Cys vs C(B)). In vitro incubation with STZ had no effect on the studied enzymes. The present data revealed a protective role for Cys towards the oxidative effect of diabetes on the adult rat brain. Moreover, an increase in whole brain AChE activity due to diabetes was recorded (not repeatedly established in the literature, since contradictory findings exist), that was further increased by Cys. The inhibition of Na(+),K(+)-ATPase reflects a possible mechanism through which untreated diabetes could affect neuronal excitability, metabolic energy production and certain systems of neurotransmission. As concerns the use of Cys as a neuroprotective agent against diabetes, our in vitro findings could be indicative of a possible protective role of Cys under different in vivo experimental conditions.

Sesamol attenuate 3-nitropropionic acid-induced Huntington-like behavioral, biochemical, and cellular alterations in rats

Sesamol (SML) obtained from sesame seeds (Sesamum indicum, Linn, Pedaliaceae) has been used as a traditional health food in India and other countries since a long time. Besides its good antioxidant activity, SML is currently receiving considerable attention in relation to neurological disorders. Therefore, the present study has been designed to explore the protective role of SML in 3-nitropropionic acid (3-NP)-induced neurotoxicity in animals. Male rats were given 3-NP (10 mg/kg) treatment for 14 days. Various behavioral observations (body weight, locomotor activity), oxidative damage (lipid peroxidation, nitrite level, superoxide dismutase, and catalase enzyme), and mitochondrial enzyme complex functions were also assessed in the striatum, cortex, and hippocampal regions of the brain. 3-NP treatment significantly impaired locomotor activity, motor coordination, body weight, oxidative damage, and mitochondrial enzyme complex functions as compared with vehicle-treated groups. SML (5, 10, and 20 mg/kg) pre-treatment significantly improved body weight, locomotor activity, motor coordination, and attenuated oxidative damage in different regions of rat brain. Besides these, SML treatment also significantly improved mitochondrial enzymes in all regions of the brain as compared with the respective control (3-NP) group. The present study suggests that SML could be used as effective agents in the management of Huntington's disease.

Suppression of NF-kappabeta signaling pathway by tocotrienol can prevent diabetes associated cognitive deficits

OBJECTIVE

The etiology of diabetes associated cognitive decline is multifactorial and involves insulin receptor down regulation, neuronal apoptosis and glutamatergic neurotransmission. The study was designed to evaluate the impact of tocotrienol on cognitive function and neuroinflammatory cascade in streptozotocin-induced diabetes.

RESEARCH DESIGN AND METHOD

Streptozotocin-induced diabetic rats were treated with tocotrienol for 10 weeks. Morris water maze was used for behavioral assessment of memory. Cytoplasmic and nuclear fractions of cerebral cortex and hippocampus were prepared for the quantification of acetylcholinesterase activity, oxidative-nitrosative stress, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), NFkappabeta and caspase-3.

RESULTS

After 10 weeks of streptozotocin injection, the rats produced significant increase in transfer latency which was coupled with enhanced acetylcholinesterase activity, increased oxidative-nitrosative stress, TNF-alpha, IL-1beta, caspase-3 activity and active p65 subunit of NFkappabeta in different regions of diabetic rat brain. Interestingly, co-administration of tocotrienol significantly and dose-dependently prevented behavioral, biochemical and molecular changes associated with diabetes. Moreover, diabetic rats treated with insulin-tocotrienol combination produced more pronounced effect on molecular parameters as compared to their per se groups.

CONCLUSIONS

Collectively, the data reveal that activation of NFkappabeta signaling pathway is associated with diabetes induced cognitive impairment and point towards the therapeutic potential of tocotrienol in diabetic encephalopathy.

Metabolic transformation of sesamol and ex vivo effect on 2,2'-azo-bis(2-amidinopropane)dihydrochloride-induced hemolysis

Sesamol (3,4-methylenedioxyphenol), a phenolic constituent in roasted sesame, was reported to exhibit various beneficial activities. To understand the metabolic transformation of sesamol in vivo, rats were given sesamol intravenously and orally. The blood samples were withdrawn via cardiopuncture at specific time points. The serum samples were assayed by high-performance liquid chromatography method before and after hydrolysis with sulfatase and beta-glucuronidase. Our results indicated that following either intravenous or oral administration, sesamol declined rapidly and the sulfate/glucuronide of sesamol emerged instantaneously. The peak serum concentration and systemic exposure of sesamol were markedly lower than sesamol sulfate/glucuronide. Ex vivo evaluation revealed that sesamol exerted profoundly higher capability against 2,2'-azo-bis(2-amidinopropane)dihydrochloride-induced hemolysis than the serum metabolites. In conclusion, sulfate and glucuronide of sesamol were the principle metabolites of sesamol in the bloodstream of rats. The conjugated metabolites of sesamol warrant more bioactivity investigations to understand the in vivo effect of sesamol.